1. Field of the Invention
The present invention relates to a flat plate laminate ozone generating apparatus including a plurality of laminated plate-shaped high voltage electrodes and low voltage electrodes between which an alternating voltage is applied to produce a discharge and generate ozone gas, and in particular, to an ozonizer which is an essential portion of the flat plate laminate ozone generating apparatus and which includes the high voltage electrodes and low voltage electrodes and to which a gas containing oxygen is supplied to generate ozone gas, and also in particular, to a construction of the ozonizer which is thin, of a large capacity and in which the number of components may be reduced while also making the apparatus small in size.
2. Description of the Related Art
FIG. 49 is a side sectional view of a conventional coaxial cylindrical ozone generating apparatus disclosed in, for example, Japanese Patent Publication Sho 59-48716. FIG. 50 is a sectional view, taken along the line L—L, of the coaxial cylindrical ozone generating apparatus of FIG. 49. In FIGS. 49 and 50, a coaxial cylindrical ozone generating apparatus includes a power source 1300 for applying a high voltage to a high voltage electrode 3, a glass dielectric tube 5 which is 40 mm in diameter and approximately 1 m in height. The high voltage electrode 3 has a conductive layer on an inner circumferential surface of the glass dielectric tube 5. A cylindrical earthed electrode tube 7 having an 50 mm outside diameter and approximately 1.2 m height is disposed coaxially with the glass dielectric tube 5 having the high voltage electrode 3. A discharge gap 106 between the cylindrical earthed electrode tube 7 and the glass dielectric tube 5 is maintained by a spring-shaped spacer 113 disposed at opposing portions of both electrodes. In a housing 1100 for housing these component parts, an inlet 1010 for supplying a raw material gas, including oxygen, and an exhaust outlet 111 are provided. Moreover, a cooling space 109 is provided at an outer circumferential side of the cylindrical earthed electrode tube 7 of the housing 1100.
The glass dielectric tube 5 forms a dual tube construction together with the cylindrical earthed electrode tube 7 and a dielectric is inserted between the cylindrical earthed electrode and the high voltage electrode 3 to form an electrode pair. A high voltage is applied to the high voltage electrode 3 to cause a discharge in the discharge gap 106 and generate ozone. In the cooling space 109, water (coolant) is flowed from a flow inlet 112a to a flow outlet 112b for cooling.
The discharge gap 106 is formed as an approximately 0.6 mm space (discharge gap) between the cylindrical earthed electrode tube 7 and the glass dielectric tube 5 by fitting the glass dielectric tube 5, with the spring-shaped spacer 113 disposed at an outer circumferential portion thereof, in the cylindrical earthed electrode tube 7. Construction is such that oxygen or air, being a raw material gas, is flowed in the discharge gap under a gas pressure of approximately 0.1 MPa and gas passing through the apparatus is taken out. Generally, in one (1) of the above ozone generating cells of a 50 mm outside diameter and approximately 1.2 m height, a power injection density is 0.2 W/cm2 or less for efficient ozone generation.
An alternating high voltage is applied between the electrodes (between the gap), which include the cylindrical earthed electrode tube 7 and the glass dielectric tube 5 formed with the high voltage electrode 3 at an inner circumferential surface thereof, and a dielectric barrier of a 0.2 W/cm2 power density is generated whereby the raw material gas is converted to an ozone gas of a 100 g/m3 ozone concentration. This generated ozone gas is continuously taken out from the exhaust port 111 with the flow of the raw material gas. Generally, in each of the above ozone generating cells, 50 mm in outside diameter and approximately 1.2 m in height, approximately 25 g/h of generated ozone may be obtained. An ozone efficiency for obtaining 1 kg/h of ozone is approximately 10 kWh/kg. Also, the volume of one (1) of these ozone generating apparatuses is 2000 cm3.
Ozone gas is used in washing semiconductors and liquid crystal production apparatuses and film and resist peeling processing. It is also used in water treatment apparatuses and pulp bleaching apparatuses and a large amount of ozone is required in these fields. The amount of ozone used in the above mentioned semiconductors and liquid crystal production fields is several tens g/h to 500 g/h, and, in addition to ozone generating performance, compactness is highly desired. For example, in only an ozonizer portion with an ozone generating capacity of 250 g/h, a width of 20 cm or less, height of 20 cm or less, depth of 50 cm or less and volume of 20000 cm3 (0.02 m3) or less is desired. Moreover, in the fields of water treatment or pulp bleaching, a large capacity of ozone, 10 to 60 kg/h, is necessary. In this case, were one to construct a 60 kg/h-class ozone generating apparatus of a plurality of the above mentioned 50 mm–1.2 m ozone generating cells, approximately 2400 (=60000 g/h/25 g/h) ozone generating cells would be required and this would be extremely large and construction and maintenance costs would be high. By simple calculation, the size of this 60 kg/h-class ozone generating apparatus would be approximately 4.8 m3 (=2400 cells×2000 cm3) and, in actuality, it would be a large apparatus, approximately 6 m3. An apparatus of a number of these ozone generating cells is shown in FIGS. 51 to 52. Although the apparatus shown includes eight (8) ozone generating cells, the conventional large apparatus is constructed as in FIG. 53; in the actual 60 kg/h-class ozone generating apparatus, construction is such that two thousand four hundred (2400) glass dielectric tubes are inserted.
In FIGS. 51 and 52, the large ozone generating apparatus includes a plurality of electrode pairs including the cylindrical earthed electrode tube and glass dielectric tube 5, 40 mm in diameter and 1 m in length, with the high voltage electrode 3 housed in the housing 1100; FIG. 51 is a side sectional view thereof and FIG. 52 is a sectional view, taken along the line LII—LII, of FIG. 51. The apparatus shown in FIGS. 51 and 52 has an abutting structure (tandem structure) in which, in the electrode pair, the glass dielectric tubes 5 are inserted in the cylindrical earthed electrode tubes 7 from both sides. These two electrode pairs disposed in tandem comprise one set of which there are four sets in all. That is, the apparatus is constructed from a total of eight electrode pairs. (See FIG. 52).
In FIGS. 54 and 55, there is shown a conventional example of a flat plate ozone generating cell laminated in multiple layers in order to make the apparatus comprising a number of 50 mm–1.2 m ozone generating cells, shown in FIGS. 51 and 52, a compact structure. This is essential portion of a conventional ozone generating apparatus disclosed in Japanese Patent Publication Laid-open No. Hei 10-25104 “Discharge Cell for Ozone Generating Apparatus”. FIG. 54 is a transverse sectional view and FIG. 55 is a vertical section taken along the line LV—LV in FIG. 54. Moreover, FIG. 54 shows a view, along the line LlV—LIV in FIG. 55, viewed from the direction of the arrows. In FIGS. 54 and 55, high frequency wave inverter portions 1300a, 1300b, 1300c for supplying power to an ozonizer 1100 are connected in the ozonizer 1100. Fuses 177a, 177b, and 177c for preventing excess current, which are electrically connected to the high frequency wave inverter portions 1300a, 1300b, and 300c, are disposed inside the ozonizer 1100. The fuses 177a, 177b, 177c are held at side surfaces of low voltage electrodes 107x, 107y via insulators.
The ozonizer 1100 includes an ozonizer cover 1110 of a cylinder-and-bottom shape with an airtight inner structure. A raw material gas inlet 1010 for supplying a raw material gas (oxygen gas) from outside to inside the ozonizer cover 1110 is provided in the ozonizer cover 1110. Two (2) plate, six (6) corner, flat low voltage electrodes 107x, 107y are provided in the ozonizer 1100. In the low voltage electrodes 107x, 107y, machined material is joined by welding so as to make cavities in respective inner portions. These inner portion cavities are, as described later, used as a cooling water passage 109. That is to say, cooling water is circulated as a coolant in inner portions of the low voltage electrodes 107x, 107y which, in addition to being electrodes, also have a heat sink function.
In the space between the two (2) plate low voltage electrodes 107x, 107y, three (3) plate disc-shaped low voltage electrodes 107xa, 107xb (107xc not shown in the drawing) are connected at a low voltage electrode 107y-side surface of the low voltage electrodes 107x. On the other hand, three (3) plate disc-shaped low voltage electrodes 107ya, 107yb (107yc not shown in the drawing) are connected at a low voltage electrode 107x-side surface of the low voltage electrodes 107y. 
Furthermore, In the space between the two (2) plate low voltage electrodes 107x, 107y, three (3) disc-shaped dielectric plates 105a, 105b, 105c are disposed facing the disc-shaped low voltage electrodes 107xa, 107xb (107xc not shown), respectively. While three (3) disc-shaped dielectric plates 105a, 105b and 105c are disposed facing the disc-shaped low voltage electrodes 107ya, 107yb (107yc not shown), respectively, at the low voltage electrode 107y-side as well. Each two (2) plate dielectric 105a, 105b and 105c forms a pair. Thin electrically conductive films 115a, 115b and 115c are formed at surfaces which face the two (2) plate, dielectric 105a, 105b, 105c pairs, respectively.
Spacers 113 are sandwiched between the low voltage electrodes 107xa, 107xb (107xc not shown) and the dielectric plates 105a, 105b and 105c. Discharge regions 106 are formed between low voltage electrodes 107xa, 107xb (107xc not shown) and dielectric plates 105a, 105b and 105c, respectively, by means of spacers 113. The discharge regions 106 are formed as an extremely small space. Similarly, discharge regions 106 are formed as an extremely small space between low voltage electrodes 107ya, 107yb (107yc not shown) and dielectric plates 105a, 105b and 105c, respectively, by means of spacers 113.
Gas sealing material 131 having elasticity is disposed between each two (2) plate dielectric pair 105a, 105b and 105c. Moreover, high voltage electrodes 103 which are thin plate electrodes are disposed between each two (2) plate dielectric pair 105a, 105b and 105c. Furthermore, gold springs 132 are disposed between each respective high voltage electrode 103 and dielectric 105a, 105b and 105c. That is, the high voltage electrodes 103 are constructed so as to be sandwiched between two (2) plate dielectrics 105a, 105b and 105c which have an elastic function. The high voltage electrodes 103 are electrically connected to surfaces of the electrically conductive films 115a, 115b and 115c of the dielectric plates 105a, 105b and 105c via the gold springs so as to supply high voltage to the dielectric plates 105a, 105b and 105c. 
In this prior art, the disc-shaped low voltage electrodes 107xa, 107xb (107xc not shown) which are to be discharge surfaces of a high degree of flatness are each connected on the low voltage electrode surface divided from the center of the six (6) corner, flat low voltage electrodes 107x, 107y into three equal sections at 120 degrees, and three (3) disc-shaped dielectric plates 105a, 105b, 105c are disposed facing the disc-shaped low voltage electrodes 107xa, 107xb (107xc not shown), respectively. Accordingly, the common low voltage electrode 107x, 107y and a discharge portion including one (1) of the dielectric plates 105a or 105b or 105c is referred to as an ozone generating discharge cell 199a, 199b (199c not shown), respectively. In this prior art, a discharge unit includes three (3) discharge cells 199a, 199b and 199c in the common low voltage electrode 107x, 107y. 
Ozone retrieving holes 128a, 128b and 128c are bored in central portions of the dielectric plates 105a or 105b and 105c. Moreover, ozone retrieval holes are also formed in the low voltage electrodes 107xa, 107xb (107xc not shown), and ozone discharge pipes 111a, 111b (111c not shown) which pass through a respective low voltage electrodes 107x are communicated in these ozone retrieval holes. Ozone gas flowing in the direction of the arrows 110 in FIG. 55 is taken out from the ozonizer 1100 The cooling water passage 109 for circulating cooling water as a coolant is formed in an inner potion of the low voltage electrode 107x, 107y. The cooling water passage 109 includes a cooling water inlet 123a and outlet 123b. A cooling water supply header 121a and cooling water discharge header 121b are connected in the inlet 123a and outlet 123b via piping 122a, 122b, respectively. Furthermore, a discharge outlet 112a of a main cooling pipe for supplying cooling water to the ozonizer 1100 from the outside is connected at the cooling water supply header 121a. Also, a discharge inlet 112b of a main cooling pipe for discharging cooling water from the ozonizer 1100 to the outside is connected at the cooling water discharge header 121b. Cooling water flows as shown by the arrow 120 in FIG. 54 and is supplied to the ozonizer 1100.
Accordingly, three (3) discharge regions 106 are provided at the main surface of the low voltage electrode 107x, 107y, and since the discharge regions 106 are also formed at both surfaces of the high voltage electrode 103, a total of six (6) discharge regions are formed. Six (6) discharge cells are formed by the spacers 113 provided in the discharge regions 106 for forming the discharge regions 106, one (1) low voltage electrode 107x, 107y set and six (6) dielectric plates 105a, 105b and 105c, and the high voltage electrode 103. Hence, (each) low voltage electrode pair 107x, 107y includes six (6) discharge regions and the structure is such that a high capacity ozonizer may be constructed.
The discharge cell structure is such that, along with the cooling water passage 109 provided in an inner portion of the low voltage electrode pair 107x, 107y, ozone gas passages are also formed and three (3) ozone gas passages are provided in the laminating direction.
Next, operation will be explained. A high voltage generated by the high frequency inverter portions 1300a, 1300b and 1300c is supplied to the dielectric plates 105a, 105b and 105c via the excess current preventing fuses 177a, 177b and 177c disposed at side surfaces of the low voltage electrode 107x, 107y, from the high voltage electrode and (finally) through the gold springs 132. A raw material gas containing oxygen is introduced from the raw material gas inlet 1010 provided in the ozonizer cover 1110 and the raw material gas is sucked into the discharge gaps 106 from the outside circumferential direction of the ozone generating discharge cells 199a, 199b and 199c, and the raw material gas becomes ozone when a silent discharge is performed in the discharge gaps 106. The ozone gas exiting the discharge gaps 106 is led to the ozone retrieving holes 128a, 128b and 128c, discharged in the ozone discharge pipes 111a, 111b and 111c in the direction shown by the arrows 110 and is taken out.
In an ozone generating apparatus constructed such as above, in order to increase the discharge surface area and, thus, capacity, a plurality of dielectric plates 105a, 105b and 105c are disposed facing the common low voltage electrode 107x, 107y so that a high capacity becomes a possible without increasing the size of the dielectric plates 105a, 105b and 105c, which must be thick in order to obtain a predetermined level of flatness. Also, the amount of ozone generated may be increased while the number of low voltage electrode parts for cooling—coupling, connected to low voltage electrode 107x, 107y, as well as parts in the low voltage electrode 107x, 107y itself, may be reduced.
Furthermore, because the plurality of discharge cells 199a, 199b and 199c are disposed effectively in the common low voltage electrode 107x, 107y, a compact apparatus may be realized. Moreover, since the disc shaped low voltage electrodes 107xa, 107xb 107xc which are discharge surfaces having a flatness of a high precision are connected in the common low voltage electrode 107x, 107y, a predetermined level of flatness may be obtained.
A dielectric barrier discharge is generated in the discharge regions 106 via the dielectric plates 105a, 105b and 105c by applying an alternating high voltage to the total of six (6) high voltage electrodes 103 arranged at main surfaces of the low voltage electrode pair 107x, 107y. Because an alternating high voltage is applied for discharge to each of the low voltage electrode pair 107x, 107y and the six (6) high voltage electrodes 103, three pairs (6) of discharge regions 106 are formed in roughly the same plane. Oxygen gas is at first disassociated into oxygen atoms and, at approximately the same time, these oxygen atoms are involved in a three-way collision with other oxygen atoms or a wall and ozone gas is simultaneously generated from the six (6) discharge regions 106, and a large quantity of ozone gas may be obtained.
Because each low voltage electrode 107x, 107y is common for three discharge regions 106, electrodes of three discharge regions may be cooled together when cooling water is flowed in the low voltage electrode 107x or 107y. 
Moreover, although this prior art is described having only one (1) low voltage electrode pair 107x, 107y, laminating modules, including the low voltage electrode pair 107x, 107y and a plurality of electrodes sandwiched there-between, in a plurality of layers is also commonly performed to increase the quantity of generated ozone gas.
Patent Publication 1: Japanese Patent Publication No. Sho 59-48761
Patent Publication 2: Japanese Patent Laid-open No. Hei 10-25104 (para. 4–5, FIGS. 1–2)
Patent Publication 3: Japanese Patent Laid-open No. Hei 11-292516